1. Field of the Invention
The present invention relates to a flaring tool for gradually spreading a front end of a pipe into a conical shape, and more particularly, it relates to a motor driven flaring device.
Upon welding or fusing a pipe to another pipe or a pipe coupling, it is necessary to spread an end of the pipe or the pipe coupling to be connected to the pipe from an inner diameter side thereof into a conical shape in order to provide a sufficient connecting surface area. To this end, a flaring device can be used.
2. Description of the Related Art
To spread a pipe end into a conical shape (e.g., 45.degree. flare), as shown in FIG. 15, a simple manual flaring tool has been used having a tool body 1 which has a rotatable shaft 7 with handle 3 at its upper end, as shown in FIG. 12. The rotatable shaft 7 is rotatably screwed in the upper end of the tool body 1. The rotatable shaft 7 is provided on its lower end with an eccentric cone 5, as shown in FIGS. 13 and 14. Upon flaring, the eccentric cone 5 is pressed against the end of the pipe P and then the handle 3 is manually rotated by an operator to rotate the eccentric cone 5 while pressing the eccentric cone 5 down onto the pipe end to thereby spread the latter into a conical shape. Thus, the pipe end is flared from the inner diameter side thereof into a conical shape corresponding to the eccentric cone 5.
As can be seen in FIGS. 13 and 14, a rotation axis Y of the eccentric cone 5 about which it rotates is inclined or eccentric with respect to the axis X of the rotatable shaft 7. However, the center of rotation of the eccentric cone 5 at the front end thereof (apex of the cone) is fixed and is always located on the axis of the rotatable shaft 7, so that the pipe end can be gradually and smoothly flared. Note, there is a phase difference of 180.degree. of the eccentric cone 5 between FIGS. 13 and 14.
In FIGS. 13 and 14, numeral 9 designates a holder plate which holds the pipe P and has an array of holes 6 in which the pipe P to be held is inserted. In the arrangement shown in FIGS. 13 and 14, although there are six different diameters of holes 6 (only three of them are shown) in which six outer diameters of pipes can be selectively inserted and held, only one hole 6 could be essentially formed in the holder plate 9. The holes 6 are chambered or tapered at the entrance ends thereof into a conical shape corresponding to the conical peripheral surface of the eccentric cone 5.
The holder plate 9 is split into two plate elements 9a and 9b (FIG. 12), each having semi-circular recesses defining the holes 6 when combined. The pipe P is first fitted in the associated hole 6 and is then firmly held therein by the holder plate 9 when a threaded handle 8 attached to the tool body 1 is fastened.
In a known manual flaring tool as mentioned above, the operator must manually rotate the handle 3 with a large operational force, which is however troublesome and inconvenient. In particular, upon flaring an end of an existing pipe which runs along a ceiling of a house, the operator is obliged to work while looking above, which is often physically not acceptable.
Furthermore, the precision of the flaring largely depends on the skill of the operator because of the manual operation, thus resulting in a loss of reliability.